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Introduction: Carbonated water (CarbW) affects the swallowing function associated with the action of the brainstem. In addition, CarbW ingestion promotes mean blood flow in the middle cerebral artery, which is associated with blood flow to the frontal and temporal lobes. In this milieu, studies regarding the effect of drinking CarbW on brain activity are of significance. In the present study, we compared the changes in cerebral blood flow in the frontal region before and after the ingestion of CarbW or uncarbonated water (SW). Methods: Near-infrared spectroscopy was used to continuously measure the cerebral blood flow at 22 channels in the frontal region of 13 healthy young adults for 10 min before and after the ingestion of CarbW or SW. We statistically compared the changes in oxyhemoglobin concentration before and after the ingestion of CarbW or SW. Results: Compared with that before CarbW ingestion, the oxyhemoglobin concentration in the left frontal region increased after CarbW ingestion. In particular, a significant increase (p < 0.05) was observed in the ch21 region. On the contrary, no marked increase or decrease in cerebral blood flow was observed after SW ingestion compared with that before ingestion. Discussion: The activated part of the frontal region (ch21) corresponds to the vicinity of the orbitofrontal cortex, which is reportedly activated by rewarding stimuli. In addition, as the orbitofrontal cortex is located at the terminal end of the reward pathway of the mesocortical system, CarbW ingestion might have acted on the dopaminergic reward pathway of the mesocortical system. [ABSTRACT FROM AUTHOR]

Stroke is a global health issue caused by reduced blood flow to the brain, which leads to severe motor disabilities. Measuring oxygen levels in the brain tissue is crucial for understanding the severity and evolution of stroke. While CT or fMRI scans are preferred for confirming a stroke due to their high sensitivity, Near-Infrared Spectroscopy (NIRS)-based systems could be an alternative for monitoring stroke evolution. This study explores the potential of fNIRS signals to assess brain tissue in chronic stroke patients along with rehabilitation therapy. To study the feasibility of this proposal, ten healthy subjects and three stroke patients participated. For signal acquisition, two NIRS sensors were placed on the forehead of the subjects, who were asked to remain in a resting state for 5 min, followed by a 30 s motor task for each hand, which consists of opening and closing the hand at a steady pace, with a 1 min rest period in between. Acomplete protocol for placing sensors and a signal processing algorithm are proposed. In healthy subjects, a measurable change in oxygen saturation was found, with statistically significant differences (females p = 0.016, males p = 0.005) between the resting-state and the hand movement conditions. This work showed the feasibility of the complete proposal, including the NIRS sensor, the placement, the tasks protocol, and signal processing, for monitoring the state of the brain tissue cerebral oxygenation in stroke patients undergoing rehabilitation therapy. Thus this is a non-invasive barin assessment test based on fNIRS with the potential to be implemented in non-controlled clinical environments. [ABSTRACT FROM AUTHOR]

Superoxide dismutase (SOD) and Catalase (CAT) play a crucial role as the first line of defense antioxidant enzymes in a living cell. These enzymes neutralize the superoxide anion from the autooxidation of oxyhemoglobin (Oxy-Hb) and convert hydrogen peroxides into water and molecular oxygen. In this study, we fabricated hemoglobin submicron particles (HbMPs) using the Coprecipitation Crosslinking Dissolution (CCD) technique and incorporating first-line antioxidant enzymes (CAT, SOD) and second-line antioxidant (ascorbic acid, Vit. C) to investigate a protective effect of modified HbMPs via cyclically oxygenation and deoxygenation. Thereafter, the total hemoglobin (Hb) content and Oxy-Hb content to HbMPs were determined. The results revealed that the HbMPs have a protective effect against oxidation from hydrogen peroxide and potentially neutralizing hydrogen peroxide to water over 16 times exposure cycles. No significant differences in total Hb content were found between normal HbMPs and enzyme-modified HbMPs in the absence of Vit. C. The Oxy-Hb of CAT-HbMPs showed significantly higher values than normal HbMPs. The functional Hb of normal HbMPs and enzyme-modified HbMPs was increased by 60–77% after a short time Vit. C (1:25) exposure. The co-immobilization of CAT and SOD in hemoglobin particles (CAT-SOD-HbMPs) in the presence of Vit. C provides protective effects against oxidation in cyclic Oxygenation and Deoxygenation and shows the lowest reduction of functional Hb. Our studies show that the CCD technique-modified HbMPs containing antioxidant enzymes and a reducing agent (ascorbic acid) demonstrate enhanced Hb functionality, providing protective effects and stability under oxidative conditions. [ABSTRACT FROM AUTHOR]

We investigate the utility of functional near-infrared spectroscopy (fNIRS) for workload-based adaptive automation through the lens of multiple resource theory. We focus on the criteria of unobtrusiveness, responsiveness, load sensitivity (low vs high load), and load diagnosticity (differentiating types of load). We report a large meta-review, in which we conclude that only a few studies were suitable for evaluating sensitivity and diagnosticity in complex real-world tasks. While these reveal that the fNIRS signal is adequately sensitive to gradations of load level changes (sensitivity), the diagnosticity of fNIRS to different sources of cognitive load remained uncertain. We manipulated mental load of a complex shape sorting task via working memory load (WM) and visual perceptual load (VL), while a secondary auditory task was present throughout. We measured the effect of these manipulations at the group-level using conventional secondary and eyetracking workload measures, as well as hemodynamic response in specific functional regions in the brain, including regions involved in multi-tasking (MT), VL, WM, and auditory load (AL). Our findings revealed that fNIRS is both sensitive and diagnostic to load in complex tasks, with greater sensitivity revealed by deoxyhemoglobin than oxyhemoglobin and the brain regions associated with diagnosticity align with neuroscience literature on perceptual load, WM, and goal-directed multitasking. [ABSTRACT FROM AUTHOR]

Transcranial direct current stimulation (tDCS) is often reported to have positive effects on brain hemodynamics as well as cognitive performance. Binaural beats (BBs) have also shown the potential to improve cognitive performance. However, we could not find any studies assessing prefrontal hemodynamics using a combination of these techniques or assessing the effects on hemodynamic response at different intensity levels of tDCS (two and three mA). This study aimed to compare the immediate hemodynamic responses to tDCS at different intensities (two and three mA) with and without 40 Hz BBs. Sixty-eight healthy young individuals of both sexes were split into four groups: the tDCS 2 mA group; tDCS 3 mA group; tDCS 2 mA + BB group; and tDCS 3 mA + BB group. All groups received 20 min tDCS (F3-Fp2) alone or combined with BBs. The hemodynamic effect was assessed using a functional near-infrared intracranial spectroscope (fNIRS) positioned on the left supraorbital region (Fp1). The mean values of rates of oxygen saturation (SatO2) were recorded at baseline, during the intervention period, and post-stimulation. The oxygenated hemoglobin rates (HbO) were also extracted. No between-group differences were observed. The within-group analysis did not show significant differences in terms of the time×groups factor. However, the time factor showed significant within-group differences. No differences were found for the HbO rates. The present findings showed that two and three mA tDCS had effects on pre-frontal cortex SatO2; however, the use of additional BBs did not change the SatO2 levels compared to the use of tDCS alone. [ABSTRACT FROM AUTHOR]

Background: Reappraisal, an emotion regulation strategy, includes reinterpretation and affect labeling involving verbalizing emotions. In general, reappraisal is supported by lateral prefrontal cortical regions, which are also known to underlie cognitive regulation. Other research has shown that affect labeling combined with reappraisal of negative emotions increases lateral prefrontal cortex activity more than reappraisal alone does, suggesting that affect labeling facilitates emotional regulation. However, the influence of affect labeling on the efficacy of reappraisal in reducing subjective negative emotions has not been determined. Methods: In the experiment, 35 participants (mean age = 28.2 years (SD = 9.63); 12 women and 23 men) viewed vignettes that aroused negative emotion. Then, they rated subjective negative emotions as baseline values. Following the baseline rating, the task branched into four conditions, combining affect labeling and emotion regulation factors. In the affect-labeling factor, participants selected emotional labels consistent with their own emotions or not. Regarding the emotion regulation factor, participants engaged in reappraisal to regulate their negative emotions. Throughout the experiment, the intensity of negative emotions was measured three times, mirroring the baseline measurement. Oxyhemoglobin (OxyHb) signal values in prefrontal cortex regions during tasks were measured by functional near-infrared spectroscopy. Results: Differences between the subjective negative emotion ratings at baseline and after reappraisal indicated that reappraisal significantly reduced negative emotion with and without affect labeling (t (1173.05) = 29.97, p < 0.001), and the combination of affect labeling and reappraisal was less effective in regulating negative emotions at the subjective level than reappraisal without affect labeling (t (1172.03) = 3.15, p < 0.01). Additionally, there was an increase in OxyHb signal in the bilateral dorsolateral prefrontal and right ventral prefrontal cortices while participants performed reappraisal with affect labeling. Conclusion: Our findings suggest that affect labeling, when performed prior to cognitive reappraisal, may influence the process of negative emotion regulation in complex ways. The interaction between affect labeling and reappraisal appears to modulate prefrontal cortex activity, potentially reflecting changes in cognitive processing during emotion regulation attempts. These results highlight the need for further investigation into the intricate relationship between different emotion regulation strategies. [ABSTRACT FROM AUTHOR]

Background/Objectives: Based on Blind Source Separation and the use of multispectral imaging, the new approach we propose in this paper aims to improve the estimation of the concentrations of the main skin chromophores (melanin, oxyhemoglobin and deoxyhemoglobin), while considering shading as a fully-fledged source. Methods: In this paper, we demonstrate that the use of the Infra-Red spectral band, in addition to the traditional RGB spectral bands of dermatological images, allows us to model the image provided by each spectral band as a mixture of the concentrations of the three chromophores in addition to that of the shading, which are estimated through four steps using Blind Source Separation. Results: We studied the performance of our new method on a database of real multispectral dermatological images of melanoma by proposing a new quantitative performances measurement criterion based on mutual information. We then validated these performances on a database of multispectral dermatological images that we simulated using our own new protocol. Conclusions: All the results obtained demonstrated the effectiveness of our new approach for estimating the concentrations of the skin chromophores from a multispectral dermatological image, compared to traditional approaches that consist of using only the RGB image by neglecting shading. [ABSTRACT FROM AUTHOR]

This study aimed to observe the impact of pure Binaural Beats (BB) stimulation in the inaudible frequency range, excluding the influence of sound, on visuospatial memory. Additionally, we investigated whether the brainwave changes induced by BB stimulation directly affect brain activation. The experiment involved 17 participants (12 males with a mean age of 23.2 ± 1.7 and 5 females with a mean age of 21.0 ± 0.7) in their 20s. Each participant received 10 Hz BB stimulation by presenting frequencies of 18,000 Hz and 18,010 Hz to the left and right ears, respectively. The experiment consisted of Rest phase (5 min), Task phase (5 min), and Rest phase (5 min). The Task phase included conditions where participants performed the task either without BB stimulation "Task only" or with BB stimulation "Task + BB". Visuospatial memory was evaluated using the 3-back task. To observe brain activation, functional Near Infrared Spectroscopy (fNIRS) was employed to measure hemodynamic responses in all phases. The cognitive task performance (Accuracy, Reaction time) and oxyhemoglobin (HbO) concentration during the Task phase were compared between conditions with and without BB stimulation using paired t-tests. Results indicated a significantly shorter Reaction time in the Task + BB condition compared to the Task only condition. Moreover, an increase in HbO concentration was observed in the F1-F3, F2-F4, and P2-P4 regions during the Task + BB condition. In conclusion, the observed increase in HbO concentration suggests a positive influence on task performance. This study is meaningful in objectively demonstrating the impact of inaudible BB stimulation on visuospatial memory, utilizing both behavioral data and direct neural activation reflected in hemodynamic responses. [ABSTRACT FROM AUTHOR]

This research is the first of its kind to assess the impact of extreme heat from a fire on the area of origin estimation (AO) for impact bloodstain patterns on surfaces commonly encountered in a domestic environment. Impact patterns were created on three replicates of drywall and metal and two replicates of glass using an impact device. Sixteen upward moving stains were selected, and the AO was calculated using HemoSpat®. The surfaces were exposed to heat from a fire, and the AO was recalculated using the same stains. Paired t-test analysis determined that there were no significant differences between the AO calculations before and after heat exposure on different surfaces. Results indicated that extreme heat accelerates the oxidation process of oxyhemoglobin, explaining the significant colour change of bloodstains after a fire. The colour change provides insight to investigators that stains at a fire scene may appear significantly aged despite being related to the incident. [ABSTRACT FROM AUTHOR]

Brief exposure to repeated episodes of low inspired oxygen, or acute intermittent hypoxia (AIH), is a promising therapeutic modality to improve motor function after chronic, incomplete spinal cord injury (SCI). Although therapeutic AIH is under extensive investigation in persons with SCI, limited data are available concerning cardiorespiratory responses during and after AIH exposure despite implications for AIH safety and tolerability. Thus, we recorded immediate (during treatment) and enduring (up to 30 min post-treatment) cardiorespiratory responses to AIH in 19 participants with chronic SCI (>1 year post-injury; injury levels C1 to T6; American Spinal Injury Association Impairment Scale A to D; mean age = 33.8 ± 14.1 years; 18 males). Participants completed a single AIH (15, 60-sec episodes, inspired O2 ≈ 10%; 90-sec intervals breathing room air) and Sham (inspired O2 ≈ 21%) treatment, in random order. During hypoxic episodes: (1) arterial oxyhemoglobin saturation decreased to 82.1 ± 2.9% (p < 0.001); (2) minute ventilation increased 3.83 ± 2.29 L/min (p = 0.008); and (3) heart rate increased 4.77 ± 6.82 bpm (p = 0.010). Considerable variability in cardiorespiratory responses was found among subjects; some individuals exhibited large hypoxic ventilatory responses (≥0.20 L/min/%, n = 11), whereas others responded minimally (<0.20 L/min/%, n = 8). Apneas occurred frequently during AIH and/or Sham protocols in multiple participants. All participants completed AIH treatment without difficulty. No significant changes in ventilation, heart rate, or arterial blood pressure were found 30 min post-AIH p > 0.05). In conclusion, therapeutic AIH is well tolerated, elicits variable chemoreflex activation, and does not cause persistent changes in cardiorespiratory control/function 30 min post-treatment in persons with chronic SCI. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the psychophysiological effects of horticultural activities on the prefrontal cortex (PFC) to understand how horticultural activities can influence mental health and cognitive function. This study involved 39 adults with an average age of 54.6 years (±12.5 years) and was conducted in a laboratory setting at Konkuk University. The impact of five different types of horticultural activities--sowing, transplanting, planting, harvesting, and packaging--on PFC oxyhemoglobin (oxy-HB) concentrations was assessed. Functional near-infrared spectroscopy (fNIRS) was used to measure oxy-HB levels in the PFC while participants engaged in each activity for 90 seconds. The results indicated that the overall PFC oxy-HB concentration was at its lowest during planting and at its highest during sowing (P < 0.001). In the right PFC, oxy-HB was also at its lowest during planting and at its highest during sowing (P < 0.01). In the left PFC, the lowest oxy-HB concentrations were observed during both planting and harvesting, whereas the highest oxy-HB concentrations were observed during transplanting and sowing (P < 0.001). Additionally, sex-based differences were noted, with females showing significantly lower oxy-HB concentrations during sowing (P < 0.05) and transplanting (P < 0.01) than those of males. These findings suggested that psychophysiological responses, as indicated by oxy-HB concentrations, vary depending on the type of horticultural activity and by sex. [ABSTRACT FROM AUTHOR]

Despite the recommendation to treat depression using transcranial direct current stimulation (tDCS), novel findings raise doubts over the tDCS's efficacy in managing depressive episodes. Neurophysiologic approaches to understanding the specificities of brain responses to tDCS in patients with depression remain to be explored. Objective: Our aim was to compare immediate hemodynamic responses to tDCS on the left dorsolateral prefrontal cortex (DLPFC; F3-Fp2 montage) in patients with depressive disorder and in controls (no additional stimuli). Methods: Sixteen participants were allocated to the depression group and sixteen to the control group. Both groups received 2 mA tDCS for 20 min, using the F3-Fp2 montage. The hemodynamic effect over the DLPFC was assessed using functional near-infrared intracranial spectroscopy (fNIRS) positioned on the left supraorbital region (Fp1). Mean, minimal, and maximal values of baseline and post-stimulation rates of oxygen saturation (SatO2) were recorded. The oxygenated hemoglobin rates (HbO) were extracted. Results: Between-group differences were detected for minimal baseline rates of SatO2 and HbO levels. The depression group showed lower results compared to the control group at baseline. After the protocol, only the depression group showed increased minimal rates of SatO2 and HbO. The post-tDCS minimal rates were equal for both groups. Conclusions: The findings showed immediate anodal tDCS effects over DLPFC hemodynamics. The effects were exclusive to the lowest baseline rate group and did not affect the normal oxygen rate group. The minimal increase in SatO2 and HbO rates after the protocol in the depression group suggests that those with reduced cerebral perfusion may be more affected by tDCS. [ABSTRACT FROM AUTHOR]

PD‐1/PD‐L1 inhibitors have emerged as standard treatments for advanced solid tumors; however, challenges such as a low overall response rate and systemic side effects impede their implementation. Hypoxia drives the remodeling of the tumor microenvironment, which is a leading reason for the failure of immunotherapies. Despite some reported strategies to alleviate hypoxia, their individual limitations constrain further improvements. Herein, a novel two‐pronged strategy is presented to efficiently address hypoxia by simultaneously adopting atovaquone (ATO, inhibiting oxygen consumption) and oxyhemoglobin (HbO2, directly supplementing oxygen) within a multifunctional aggregate termed NPs‐aPD‐1/HbO2/ATO. In addition to eliminating hypoxia with these two components, this smart aggregate also includes albumin and an ROS‐responsive cross‐linker as a controlled release scaffold, along with PD‐1 antibody (aPD‐1) for immunotherapy. Intriguingly, NPs‐aPD‐1/HbO2/ATO demonstrates exceptional tumor targeting in vivo, exhibiting ≈4.2 fold higher accumulation in tumors than in the liver. Consequently, this aggregate not only effectively mitigates hypoxia and significantly assists aPD‐1 immunotherapy but also simultaneously resolves the targeting and systemic toxicity issues associated with individual administration of each component. This study proposes substantial implications for drug‐targeted delivery, addressing tumor hypoxia and advancing immunotherapy, providing valuable insights for advancing cancer treatment strategies. [ABSTRACT FROM AUTHOR]

IntroductionCarbonated water (CarbW) affects the swallowing function associated with the action of the brainstem. In addition, CarbW ingestion promotes mean blood flow in the middle cerebral artery, which is associated with blood flow to the frontal and temporal lobes. In this milieu, studies regarding the effect of drinking CarbW on brain activity are of significance. In the present study, we compared the changes in cerebral blood flow in the frontal region before and after the ingestion of CarbW or uncarbonated water (SW).MethodsNear-infrared spectroscopy was used to continuously measure the cerebral blood flow at 22 channels in the frontal region of 13 healthy young adults for 10 min before and after the ingestion of CarbW or SW. We statistically compared the changes in oxyhemoglobin concentration before and after the ingestion of CarbW or SW.ResultsCompared with that before CarbW ingestion, the oxyhemoglobin concentration in the left frontal region increased after CarbW ingestion. In particular, a significant increase (p

Determining the level of venous oxygen saturation simultaneously with the saturation of the arterial blood with oxygen allows you to control the oxygen delivery in peripheral tissues of the body. We studied the change in the magnitude of venous blood oxygen saturation during laser-stimulated photodissociation of oxy -hemoglobin. It is shown that only strong changes in the saturation of arterial blood with oxygen lead to a change in the level of venous oxygen saturation. The original optical technique for measurement of venous and arterial blood saturation based on the pulseoximetry is presented [ABSTRACT FROM AUTHOR]

Although the gasotransmitter hydrogen sulfide (H2S) is well known for its vasodilatory effects, H2S also exhibits vasoconstricting properties. Herein, it is demonstrated that administration of H2S as intravenous sodium sulfide (Na2S) increased blood pressure in sheep and rats, and this effect persisted after H2S has disappeared from the blood. Inhibition of the L‐type calcium channel (LTCC) diminished the hypertensive effects. Incubation of Na2S with whole blood, red blood cells, methemoglobin, or oxyhemoglobin produced a hypertensive product of H2S, which is not hydrogen thioperoxide, metHb‐SH− complexes, per‐/poly‐ sulfides, or thiolsulfate, but rather a labile intermediate. One‐electron oxidation of H2S by oxyhemoglobin generated its redox cousin, sulfhydryl radical (HS•). Consistent with the role of HS• as the hypertensive intermediate, scavenging HS• inhibited Na2S‐induced vasoconstriction and activation of LTCCs. In conclusion, H2S causes vasoconstriction that is dependent on the activation of LTCCs and generation of HS• by oxyhemoglobin. [ABSTRACT FROM AUTHOR]

Subthreshold depression is an essential precursor and risk factor for major depressive disorder, and its accurate identification and timely intervention are important for reducing the prevalence of major depressive disorder. Therefore, we used functional near-infrared spectroscopic imaging (fNIRS) to explore the characteristics of the brain neural activity of college students with subthreshold depression in the verbal fluency task. A total of 72 subthreshold depressed college students (SDs) and 67 healthy college students (HCs) were recruited, and all subjects were subjected to a verbal fluency task (VFT) while a 53-channel fNIRS device was used to collect the subjects' cerebral blood oxygenation signals. The results of the independent samples t -test showed that the mean oxyhemoglobin in the right dorsolateral prefrontal (ch34, ch42, ch45) and Broca's area (ch51, ch53) of SDs was lower than that of HCs. The peak oxygenated hemoglobin of SDs was lower in the right dorsolateral prefrontal (ch34) and Broca's area (ch51, ch53).The brain functional connectivity strength was lower than that of HCs. Correlation analysis showed that the left DLPFC and Broca's area were significantly negatively correlated with the depression level. SDs showed abnormally low, inadequate levels of brain activation and weak frontotemporal brain functional connectivity. The right DLPFC has a higher sensitivity for the differentiation of depressive symptoms and is suitable as a biomarker for the presence of depressive symptoms. Dysfunction in Broca's area can be used both as a marker of depressive symptoms and as a biomarker, indicating the severity of depressive symptoms. • Hypoperfusion in right DLPFC and Broca's area is physiological mechanisms distinguishing subthreshold depression. • Higher depression is associated with lower levels of cortical activation in the left DLPFC and Broca's area. • Subthreshold depression can be associated with low strength of overall brain functional connectivity. • fNIRS may be a potential tool to improve diagnostic accuracy for subthreshold depression. [ABSTRACT FROM AUTHOR]

Background: The ability of hemoglobin to bind and dissociate oxygen is crucial in delivering oxygen to tissues and is influenced by a range of physiological states, compensatory mechanisms, and pathological conditions. This may be illustrated by the oxyhemoglobin dissociation curve (ODC). The key parameter for evaluating the oxygen affinity to hemoglobin is p50. The aim of this study was to evaluate the impact of hemodialysis on p50 in a group of patients with chronic kidney disease (CKD). An additional goal was to assess the correlation between p50 and the parameters of erythropoiesis, point-of-care testing (POCT), and other laboratory parameters. Methods: One hundred and eighty patients (106 male, 74 female), mean age 62.5 ± 17 years, with CKD stage G4 and G5 were enrolled in this cross-sectional study. Patients were divided into two groups, including 65 hemodialysis (HD) patients and 115 patients not receiving dialysis (non-HD). During the standard procedure of arteriovenous fistula creation, blood samples from the artery (A) and the vein (V) were taken for POCT. The causes of CKD, as well as demographic and comorbidity data, were obtained from medical records and direct interviews. Results: The weekly dose of erythropoietin was higher in HD patients than in non-HD patients (4914 ± 2253 UI vs. 403 ± 798 UI, p < 0.01), but hemoglobin levels did not differ between these groups. In the group of non-HD patients, more advanced metabolic acidosis (MA) was found, compared to the group with HD. In arterial and venosus blood samples, the non-HD group had significantly lower pH, pCO2 and HCO3−. This group had a higher proportion of individuals with MA with HCO3− < 22 mmol/L (42% vs. 24%, p < 0.01). The absolute difference of p50 in arterial and venous blood was determined using the formula Δp50 = (p50-A) − (p50-V). Δp50 was significantly higher in the HD group in comparison to non-HD (0.08 ± 2.05 mmHg vs. −0.66 ± 1.93 mmHg, p = 0,02). There was a negative correlation between pH and the p50 value in arterial (pH-A vs. p50-A, r = −0.56, p < 0.01) and venous blood (pH-V vs. p50-V, r = −0.45, p < 0.01). In non-HD patients, hemoglobin levels correlated negatively with p50 (r = −0.29, p < 0.01), whereas no significant relation was found in HD patients. Conclusions: The ODC in pre-dialysis CKD (non-HD) patients is shifted to the right due to MA, and this is an additional factor influencing erythropoiesis. Hemodialysis restores the natural differences in hemoglobin's dissociation characteristics in the arterial and venous circulation. [ABSTRACT FROM AUTHOR]

Participant movement is a major source of artifacts in functional near-infrared spectroscopy (fNIRS) experiments. Mitigating the impact of motion artifacts (MAs) is crucial to estimate brain activity robustly. Here, we suggest and evaluate a novel application of the nonlinear Hammerstein–Wiener model to estimate and mitigate MAs in fNIRS signals from direct-movement recordings through IMU sensors mounted on the participant's head (head-IMU) and the fNIRS probe (probe-IMU). To this end, we analyzed the hemodynamic responses of single-channel oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) signals from 17 participants who performed a hand tapping task with different levels of concurrent head movement. Additionally, the tapping task was performed without head movements to estimate the ground-truth brain activation. We compared the performance of our novel approach with the probe-IMU and head-IMU to eight established methods (PCA, tPCA, spline, spline Savitzky–Golay, wavelet, CBSI, RLOESS, and WCBSI) on four quality metrics: SNR, △AUC, RMSE, and R. Our proposed nonlinear Hammerstein–Wiener method achieved the best SNR increase (p < 0.001) among all methods. Visual inspection revealed that our approach mitigated MA contaminations that other techniques could not remove effectively. MA correction quality was comparable with head- and probe-IMUs. [ABSTRACT FROM AUTHOR]

Cupping therapy is a popular intervention for improving muscle recovery after exercise although clinical evidence is weak. Previous studies demonstrated that cupping therapy may improve microcirculation of the soft tissue to accelerate tissue healing. However, it is unclear whether the cupping size could affect the spatial hemodynamic response of the treated muscle. The objective of this study was to use 8-channel near-infrared spectroscopy to assess this clinical question by assessing the effect of 3 cupping sizes (35, 40, and 45 mm in inner diameter of the circular cup) under −300 mmHg for 5 min on the muscle hemodynamic response from the area inside and outside the cup, including oxyhemoglobin and deoxy-hemoglobin in 18 healthy adults. Two-way factorial design was used to assess the interaction between the cupping size (35, 40, and 45 mm) and the location (inside and outside the cup) and the main effects of the cupping size and the location. The two-way repeated measures ANOVA demonstrated an interaction between the cupping size and the location in deoxy-hemoglobin (P = 0.039) but no interaction in oxyhemoglobin (P = 0.100), and a main effect of the cup size (P = 0.001) and location (P = 0.023) factors in oxyhemoglobin. For the cupping size factor, the 45-mm cup resulted in a significant increase in oxyhemoglobin (5.738±0.760 μM) compared to the 40-mm (2.095±0.312 μM, P<0.001) and 35-mm (3.134±0.515 μM, P<0.01) cup. Our findings demonstrate that the cupping size and location factors affect the muscle hemodynamic response, and the use of multi-channel near-infrared spectroscopy may help understand benefits of cupping therapy on managing musculoskeletal impairment. [ABSTRACT FROM AUTHOR]

In today’s world, where stress and busyness are an integral part of everyday life, energy drinks have become not only a means of satisfying the need for energy and maintenance of vitality, but also a symbol of lifestyle, an important element of the modern culture of consumption. The speed and efficiency they promise attract the attention of consumers, especially those who are constantly on the move. Such drinks have become popular not only among young people, but also among everyone who seek to maintain their activity and efficiency during the day. The purpose of the work was to investigate the dynamics of changes in the level of total hemoglobin and its forms, in particular oxy-, carboxy-, sulf-, met-, and dyshemoglobin under the conditions of energy drink consumption. The study was conducted using male Wistar rats weighing 150–220 g kept in the vivarium under appropriate lighting conditions, temperature, humidity and standard diet. All the animals had free access to feed (based on daily requirements) and water (based on 20 ml of water per rat per day). The experiment was carried out in compliance with the requirements of the European Convention for the Protection of Vertebrate Animals used for Experimental and Scientific Purposes (Strasbourg, 1986). The animals were divided into five groups: the 1st group received drinking water (intact control); the 2nd–5th groups received daily the non-alcoholic energy drink “Burn” per os for a month. The calculation of the required amount of drink for administration per one rat was based per 1 kg of body weight. To monitor the growth and development, we weighted the rats at the beginning and at each stage of the experiment. The material (blood) was taken on the 1st (2nd group), 10th (3rd group), 20th (4th group) and 30th day (5th group) after the completion of the experiment under anesthesia (intramuscularly sodium thiopental, 60 mg/kg). The total hemoglobin level was determined with the Mythic 18 hematological analyzer. Determination of the content of oxyhemoglobin, methemoglobin, sulfhemoglobin and carboxyhemoglobin was performed spectrophotometrically. The obtained data indicate significant changes in both the total level of hemoglobin and its ligand forms, in particular, a decrease in the level of oxyhemoglobin and the accumulation of dyshemoglobins, such as methemoglobin, sulfhemoglobin, and carboxyhemoglobin. As evidenced by the obtained results, the consumption of energy drinks leads to the oxygen homeostasis violation, the development of tissue hypoxia and can cause structural and functional disorders in the body under such conditions.

Climbing performance is greatly dependent on the endurance of the finger flexors which, in turn, depends on the ability to deliver and use oxygen within the muscle. Near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) have provided new possibilities to explore these phenomena in the microvascular environment. The aim of the present study was to explore climbing-related microvascular adaptations through the comparison of the oxygen concentration and hemodynamics of the forearm between climbers and non-climber active individuals during a vascular occlusion test (VOT). Seventeen climbers and fifteen non-climbers joined the study. Through NIRS and DCS, the oxyhemoglobin (O2Hb) and deoxyhemoglobin (HHb) concentrations, tissue saturation index (TSI), and blood flow index (BFI) were obtained from the flexor digitorum profundus during the VOT. During the reactive hyperemia, climbers presented greater blood flow slopes (p = 0.043, d = 0.573), as well as greater O2Hb maximum values (p = 0.001, d = 1.263) and HHb minimum values (p = 0.009, d = 0.998), than non-climbers. The superior hemodynamics presented by climbers could indicate potential training-induced structural and functional adaptations that could enhance oxygen transportation to the muscle, and thus enhance muscle endurance and climbing performance. [ABSTRACT FROM AUTHOR]

Introduction: Moderate hypoxia may impact cognitive and sensorimotor performance prior to self-recognized impairments. Therefore, rapid and objective assessment tools to identify people at risk of impaired function during moderate hypoxia is needed. Purpose: Test the hypothesis that reductions in arterial oxygen saturation during moderate normobaric hypoxia (FiO2 = 14%) decreases gamified sensorimotor performance as measured by alterations of motor acuity. Methods: Following three consecutive days of practice, thirty healthy adults (25 ± 5 y, 10 females) completed three bouts of the tablet-based gamified assessment (Statespace Labs, Inc.) of motor acuity at Baseline and 60 and 90 min after exposure to 13.8 ± 0.2% (hypoxia) and 20.1 ± 0.4% (normoxia) oxygen. The gamified assessment involved moving the tablet to aim and shoot at targets. Both conditions were completed on the same day and were administered in a single-blind, block randomized manner. Performance metrics included shot time and shot variability. Arterial oxyhemoglobin saturation estimated via forehead pulse oximetry (SpO2). Data were analyzed using linear mixed effects models. Results: Compared to normoxia (99±1%), SpO2 was lower (p<0.001) at 60 (89±3%) and 90 (90±2%) min of hypoxia. Shot time was unaffected by decreases in SpO2 (0.012, p = 0.19). Nor was shot time affected by the interaction between SpO2 decrease and baseline performance (0.006, p = 0.46). Shot variability was greater (i.e., less precision, worse performance) with decreases in SpO2 (0.023, p = 0.02) and depended on the interaction between SpO2 decrease and baseline performance (0.029, p< 0.01). Conclusion: Decreases in SpO2 during moderate hypoxic exposure hinders sensorimotor performance via decreased motor acuity, i.e., greater variability (less precision) with no change in speed with differing decreases in SpO2. Thus, personnel who are exposed to moderate hypoxia and have greater decreases in SpO2 exhibit lower motor acuity, i.e., less precise movements even though decision time and movement speed are unaffected. [ABSTRACT FROM AUTHOR]

Transcranial direct current stimulation (tDCS) is often reported to have positive effects on brain hemodynamics as well as cognitive performance. Binaural beats (BBs) have also shown the potential to improve cognitive performance. However, we could not find any studies assessing prefrontal hemodynamics using a combination of these techniques or assessing the effects on hemodynamic response at different intensity levels of tDCS (two and three mA). This study aimed to compare the immediate hemodynamic responses to tDCS at different intensities (two and three mA) with and without 40 Hz BBs. Sixty-eight healthy young individuals of both sexes were split into four groups: the tDCS 2 mA group; tDCS 3 mA group; tDCS 2 mA + BB group; and tDCS 3 mA + BB group. All groups received 20 min tDCS (F3-Fp2) alone or combined with BBs. The hemodynamic effect was assessed using a functional near-infrared intracranial spectroscope (fNIRS) positioned on the left supraorbital region (Fp1). The mean values of rates of oxygen saturation (SatO2) were recorded at baseline, during the intervention period, and post-stimulation. The oxygenated hemoglobin rates (HbO) were also extracted. No between-group differences were observed. The within-group analysis did not show significant differences in terms of the time×groups factor. However, the time factor showed significant within-group differences. No differences were found for the HbO rates. The present findings showed that two and three mA tDCS had effects on pre-frontal cortex SatO2; however, the use of additional BBs did not change the SatO2 levels compared to the use of tDCS alone.

Background/Objectives: Based on Blind Source Separation and the use of multispectral imaging, the new approach we propose in this paper aims to improve the estimation of the concentrations of the main skin chromophores (melanin, oxyhemoglobin and deoxyhemoglobin), while considering shading as a fully-fledged source. Methods: In this paper, we demonstrate that the use of the Infra-Red spectral band, in addition to the traditional RGB spectral bands of dermatological images, allows us to model the image provided by each spectral band as a mixture of the concentrations of the three chromophores in addition to that of the shading, which are estimated through four steps using Blind Source Separation. Results: We studied the performance of our new method on a database of real multispectral dermatological images of melanoma by proposing a new quantitative performances measurement criterion based on mutual information. We then validated these performances on a database of multispectral dermatological images that we simulated using our own new protocol. Conclusions: All the results obtained demonstrated the effectiveness of our new approach for estimating the concentrations of the skin chromophores from a multispectral dermatological image, compared to traditional approaches that consist of using only the RGB image by neglecting shading.

Despite the recommendation to treat depression using transcranial direct current stimulation (tDCS), novel findings raise doubts over the tDCS’s efficacy in managing depressive episodes. Neurophysiologic approaches to understanding the specificities of brain responses to tDCS in patients with depression remain to be explored. Objective: Our aim was to compare immediate hemodynamic responses to tDCS on the left dorsolateral prefrontal cortex (DLPFC; F3-Fp2 montage) in patients with depressive disorder and in controls (no additional stimuli). Methods: Sixteen participants were allocated to the depression group and sixteen to the control group. Both groups received 2 mA tDCS for 20 min, using the F3-Fp2 montage. The hemodynamic effect over the DLPFC was assessed using functional near-infrared intracranial spectroscopy (fNIRS) positioned on the left supraorbital region (Fp1). Mean, minimal, and maximal values of baseline and post-stimulation rates of oxygen saturation (SatO2) were recorded. The oxygenated hemoglobin rates (HbO) were extracted. Results: Between-group differences were detected for minimal baseline rates of SatO2 and HbO levels. The depression group showed lower results compared to the control group at baseline. After the protocol, only the depression group showed increased minimal rates of SatO2 and HbO. The post-tDCS minimal rates were equal for both groups. Conclusions: The findings showed immediate anodal tDCS effects over DLPFC hemodynamics. The effects were exclusive to the lowest baseline rate group and did not affect the normal oxygen rate group. The minimal increase in SatO2 and HbO rates after the protocol in the depression group suggests that those with reduced cerebral perfusion may be more affected by tDCS.

Background: Methemoglobinemia is one of the rare causes of cyanosis, encountered in the Emergency Department. It can be congenital or acquired, affecting the oxygen binding capacity of hemoglobin, thus shifting the oxyhemoglobin dissociation curve to the left. It is potentially life-threatening, but it responds well to specific therapies, if recognized and intervened early. MetHb levels >70% are often described as incompatible with life. Case: Here, we describe two cases of near-fatal MH (MetHb levels >70%), one with intentional and the other with accidental ingestion of substance-producing MH, and its management which highlights how timely diagnosis and prompt appropriate treatment in the Emergency Department can be lifesaving. Both cases were at physiological extremes on arrival to the ED. However, the early clinical suspicion and prompt diagnosis of methemoglobinemia, which was confirmed by blood co-oximetry, helped expedite the delivery of specific anti-dote for methemoglobin, i.e., intravenous methylene blue. Both patients responded well to the treatment and were hemodynamically stable within 6 hours. Conclusion: Cyanosis, which does not respond to oxygen, and low saturation levels not responding to oxygen therapy should raise the suspicion of Methemoglobinemia (MH). Early diagnosis and prompt administration of methylene blue are the key factors for survival. [ABSTRACT FROM AUTHOR]

Contact with the natural environment has positive effects on physical and mental health and well-being. This study aimed to investigate the effects of tactile stimulation on the psychophysiological responses of adults, using natural gardening elements. The participants were 30 adults (20–60 years old). The participants received tactile stimulation by touching five natural elements with their hands and feet, and tactile stimulation for each natural element was performed for 90 s. Geranium, tiny ardisia, decomposed granite soil, log hardwood, and culture soil were used as tactile stimulation factors for the hand, and moss, grass, pebble, bark, and culture soil were used as tactile stimulation factors for the foot. Oxyhemoglobin (oxy-Hb) concentrations in the prefrontal cortex during the stimulation as well as blood pressure and pulse rate after each activity were measured. Additionally, the semantic differential method was used to evaluate the psychological effects of contact with the elements on the participants. Compared to before tactile stimulation, the oxy-Hb concentration related to prefrontal lobe cortical activity significantly decreased in some sections using tiny ardisia, log hardwood, and culture soil on the hands, and using grass, moss, pebble, and bark on the feet. Blood pressure also showed a significant decrease after tactile stimulation using geranium, tiny ardisia, and log hardwood. The findings of this study suggest that tactile stimulation using natural gardening elements could be a significant intervention in inducing physiological stability and reducing stress by calming the activity of the prefrontal cortex. [ABSTRACT FROM AUTHOR]

The development of coronavirus infection prevents the transport of oxygen to the tissues through the mechanism of impaired hemoglobin saturation in the damaged lung. The change in the affinity of hemoglobin for oxygen, which is the most important factor in compensating for oxygen deficiency in various pathological conditions, underlies the processes of adaptation to hypoxia. The question of the significance of the shift in the oxyhemoglobin dissociation curve in this pathology is actively discussed, in which its shift to the left in the arterial blood and its shift to the right in the venous blood are noted, which in the conditions of the development of the hypoxic syndrome reflects the activation of the body's mechanisms to compensate for oxygen deficiency. The change in its position is not specific for this pathology, but is determined by the severity of oxygen deficiency and the imbalance of the mechanisms of the cardiorespiratory system, as well as the peculiarities of the status of patients and the analyzed blood sample. [ABSTRACT FROM AUTHOR]

The skin has emerge as a compelling subject for investigation owing to its accessibility and the relatively straightforward application of optical procedures to it. Diffusive reflection spectroscopy (DRS) was employed to study the influence of probe pressure on human skin. A comprehensive non-invasive study was conducted, which covers almost all the important body parts for in vivo measurements. Reflection spectra were measured for the fingertip, forearm, forehead, neck, and foot under a set of probe pressures (0–265 kPa). Importantly, each tissue type's unique composition and morphology influenced the shape, size, intensity, and position of the recorded peak, highlighting the tissue-specific responses to pressure. In addition, time-based reflection spectroscopy was also performed on the forearm under blood occlusion for 5 min to study the effect. DRS measurements were performed on volunteers of different skin tones, including dark, medium, and fair. Later, a change in the intensity of the oxyhemoglobin peak was confirmed using a green laser light of a wavelength of 532 nm. Besides the dermal studies, diffusive reflection spectroscopy was also employed to investigate the probe pressure effect on human nails. A probe pressure ranging from 0 to 385 kPa was applied for nail spectroscopy. The same trend of intensity change was observed following the previous measurements. The suggested sensing system may be crucial in applications requiring pressure sensing when the human body is subjected to varying pressures, such as exercise, weightlifting, and other sports. [ABSTRACT FROM AUTHOR]

The observation of action seems to involve the generation of the internal representation of that same action in the observer, a process named motor resonance (MR). The objective of this study was to verify whether an experimental paradigm of action observation in a laboratory context could elicit cortical motor activation in 21 early Parkinson's disease (PD) patients compared to 22 controls. Participants were instructed to simply observe (observation-only session) or to respond (Time-to-contact detection session) at the instant the agent performed a grasping action toward a graspable or ungraspable object. We used functional near-infrared spectroscopy with 20 channels on the motor and premotor brain areas and event-related desynchronization of alpha-mu rhythm. In both groups, response times were more accurate in graspable than ungraspable object trials, suggesting that motor resonance is present in PD patients. In the Time-to-contact detection session, the oxyhemoglobin levels and alpha-mu desynchronization prevailed in the graspable object trials rather than in the ungraspable ones. This study demonstrates the preservation of MR mechanisms in early PD patients. The action observation finalized to a consequent movement can activate cortical networks in patients with early PD, suggesting early rehabilitation interventions taking into account specific observation paradigms preceding motor production. [ABSTRACT FROM AUTHOR]

Human blood gas stability data is limited to small sample sizes and questionable statistical techniques. We sought to determine the stability of blood gases under room temperature and slushed iced conditions in patients using survival analyses. Whole blood samples from ∼200 patients were stored in plastic syringes and kept at room temperature (22–24 °C) or in slushed ice (0.1–0.2 °C) before analysis. Arterial and venous pO2 (15–150 mmHg), pCO2 (16–72 mmHg), pH (6.73–7.52), and the CO-oximetry panel [total hemoglobin (5.4–19.3 g/dL), percentages of oxyhemoglobin (O2Hb%, 20–99%), carboxyhemoglobin (COHb, 0.1–5.4%) and methemoglobin (MetHb, 0.2–4.6%)], were measured over 5-time points. The Royal College of Pathologists of Australasia's (RCPA's) criteria determined analyte instability. Survival analyses identified storage times at which 5% of the samples for various analytes became unstable. COHb and MetHb were stable up to 3 h in slushed ice and at room temperature; pCO2, pH was stable at room temperature for about 60 min and 3 h in slushed ice. Slushed ice shortened the storage time before pO2 became unstable (from 40 to 20 min), and the instability increased when baseline pO2 was ≥60 mmHg. The storage time for pO2, pCO2, pH, and CO-oximetry, when measured together, were limited by the pO2. When assessing pO2 in plastic syringes, samples kept in slushed ice harm their stability. For simplicity's sake, the data support storage times for blood gas and CO-oximetry panels of up to 40 min at room temperature if following RCPA guidelines. [ABSTRACT FROM AUTHOR]

Background: Inhibitory control (IC), an important component of executive function, plays an important role in the overall development of children and has not been better studied in the field of equine-assisted activity (EAA). Therefore, this study investigated the effects of EAA on IC and the underlying brain neural mechanisms in children aged 7–8 years. Methods: Forty-eight healthy children aged 7–8 years from the Maple Leaf International School-Xi’an were randomly allocated to the equine-assisted activities group (EAAG) and control group (CG). The EAAG received 12 weeks of EAAG training from instructors at the MingLiu Horse Club while the CG continued their normal daily activities. The Flanker task was administered to both groups to assess IC pre- and post-intervention. Functional nearinfrared spectroscopy (fNIRS) data were collected during the Flanker task to examine the underlying neural mechanisms. Results: Our findings indicate that after 12 weeks of EAA, the EAAG performed significantly better on the Flanker tasks than the CG, with congruent and incongruent higher accuracy and faster reaction (p < 0.01). Importantly, fNIRS data analysis revealed increased oxyhemoglobin levels in the right dorsolateral prefrontal cortex (R-DLPFC) (p < 0.05) of the EAAG during the Flanker congruent task after the EAA intervention. Conclusions: Collectively, EAA demonstrated a positive impact on IC and could effectively activate R-DLPFC in children aged 7–8 years. Furthermore, it enhanced the activation of the brain regions related to IC and increased cognitive ability in children aged 7–8 years. [ABSTRACT FROM AUTHOR]

Functional near-infrared spectroscopy (fNIRS) is a non-invasive technique frequently used to measure the brain hemodynamic activity in applications to evaluate affective disorders and stress. Using two wavelengths of light, it is possible to monitor relative changes in the concentrations of oxyhemoglobin and deoxyhemoglobin. Besides, the spatial asymmetry in the prefrontal cortex activity has been correlated with the brain response to stressful situations. We measured prefrontal cortex activity with a NIRS multi-distance device during a baseline period, under stressful conditions (e.g., social stress), and after a recovery phase. We calculated a laterality index for the contaminated brain signal and for the brain signal where we removed the influence of extracerebral hemodynamic activity by using a short channel. There was a significant right lateralization during stress when using the contaminated signals, consistent with previous investigations, but this significant difference disappeared using the corrected signals. Indeed, exploration of the susceptibility to contamination of the different channels showed non-homogeneous spatial patterns, which would hint at detection of stress from extracerebral activity from the forehead. There was no recovery phase between the social and the arithmetic stressor, a cumulative effect was not considered. Extracerebral hemodynamic activity provided insights into the pertinence of short channel corrections in fNIRS studies dealing with emotions. It is important to consider this issue in clinical applications including modern monitoring systems based on fNIRS technique to assess emotional states in affective disorders. • Stress increases are captured by fNIRS optodes on the forehead. • Extracerebral activity contributes to the prefrontal cortex (PFC) asymmetry index. • Heterogeneous extracerebral activity impacts fNIRS sensitivity to stress recovery. [ABSTRACT FROM AUTHOR]

Our main objective was to validate that hyperspectral imaging via a new portable camera carries the potential to provide a reliable clinical biomarker that can predict DFU healing. We recruited patients with diabetic foot ulceration (DFU) without peripheral arterial disease, infection or other serious illness. Using an hyperspectral imaging (HSI) apparatus, post‐debridement hyperspectral images were taken evaluating the ulcer size, periwound oxyhemoglobin (OxyHb), deoxyhemoglobin level (DeoxyHb) and oxygen saturation (O2Sat) for four consecutive visits. Twenty‐seven patients were followed, out of whom seven healed their DFU while the remaining 20 failed to heal their DFU. The average time between each visit was 3 weeks. Binary logistic regression of healers versus non‐healers on Visit 1 oxyHb and on Visit 2 showed a significant inverse association, OR = 0.85 (95% CI: 0.73–0.98, p < 0.001). An inverse correlation was observed between the Visit 1 oxyHb and the percentage of ulcer size reduction between Visit 1 and Visit 4 (r = −0.46, p = 0.02) and between the Visit 2 oxyHb and the percentage of ulcer size reduction between Visits 2 and 4 (r = −0.65, p = 0.001). Using oxyHb 50 as the cut‐off point to predict DFU complete healing, Visit 1 oxyHb measurement provided 85% sensitivity, 70% specificity, 50% positive predictive value and 93% negative predictive value. For Visit 2, oxyHb had 85% sensitivity, 85% specificity, 66% positive predictive value and 94% negative predictive value. We conclude that this preliminary study, which involved a relatively small number of patients, indicates that hyperspectral imaging is a simple exam that can easily be added to daily clinical practice and has the potential to provide useful information regarding the healing potential of DFU over a short period of time. [ABSTRACT FROM AUTHOR]

The influence of hemoglobin and cytochrome с on the decomposition of the nitrosyl iron complex with thiosulfate ligands was studied. Oxyhemoglobin stabilizes the complex, the rate of NO generation decreases. Nitrosylated hemoglobin is formed in a mixture of methemoglobin with complex under anaerobic conditions. The complex reduces ferricytochrome с. [Display omitted] Nitrosyl complexes of non-heme iron (NICs) are the depot of nitric monoxide (NO) in the body. They nitrosylate heme-containing proteins in the process of decomposition. In this work, we studied the interaction of the thiosulfate complex Na 2 [Fe 2 (S 2 O 3) 2 (NO) 4 ]·4H 2 O (complex 1), as a promising drug agent, with hemoglobin and cytochrome c. It was found that complex 1 and its decomposition products are adsorbed on the surface of oxyhemoglobin, leading to longer NO generation compared to an aqueous buffer solution. In the system with metHb, the accumulation of the product (nitrosyl hemoglobin) occurs only under anaerobic conditions. The article also presents experimental data on the nitrosylation of ferro- and ferricytochrome c (cyt c2+ and cyt c3+, respectively) in the presence of complex 1. Cyt c2+ forms the product (NO)cyt c2+, which serves as the "depot" form of NO. This protein has a lesser stabilizing effect on complex 1 compared to hemoglobin. In the system with cyt c3+, nitrosylation of protein occurs during mixing, due to the presence of an oxidizing agent K 3 [Fe(CN) 6 ]. [ABSTRACT FROM AUTHOR]

Cerebrospinal fluid (CSF) reflects biochemical changes in the brain due to its direct contact with brain interstitial fluid, making it a valuable tool for diagnosing and monitoring disease progression and therapeutic effectiveness in clinical practice. However, collecting CSF in animal studies, particularly from small animals like rat pups or mice, poses significant challenges. After attempting various reported protocols, we encountered difficulties in consistently obtaining sufficient CSF from rat pups (P7-P42). Consequently, we modified these methods and developed a protocol with controllable and precise parameters for each step, enhancing reproducibility across different researchers. The newly developed method enables rapid, single-operator, and reproducible CSF extraction while ensuring high-quality (the absorbance of the "quality control solution" at 415 nm < 0.05 AU, an indicator of oxyhemoglobin contamination for the collected CSF samples) and high-yield samples (33 ± 2.128 μL for P7 pups, 34.10 ± 2.747 μL for P8 pups, 36.67 ± 3.997 μL for P9 pups, 36.90 ± 1.946 μL for P10 pups, 35.11 ± 3.285 μL for P10 hypoxic-ischemic brain damage (HIBD) pups and 51.70 ± 5.256 μL for P42 pups, respectively). Unlike existing methods of CSF extraction in rat pups, our protocol has reproducible capillary pipette pulling parameters, controllable CSF quality indexes, and can be operated by a single person with high yield in a short time. This paper provides a step-by-step comparison and discussion of the CSF collection process, establishing a method that enables a single operator to collect CSF rapidly, consistently, sufficiently, and with controlled quality. • Cerebrospinal fluid (CSF) is crucial in both clinical diagnosis of neurological disorders and scientific research. • It is important to avoid blood contamination during CSF collection. • Obtaining sufficient and high-quality CSF from rat pups (P7-P42) is currently challenging. • This modified method enables a single operator to collect CSF efficiently with high yield and quality. [ABSTRACT FROM AUTHOR]

• Optical imaging provides an inexpensive technique for monitoring ischemic brain. • Spreading depolarizations (SD) are coupled with transient flow and hemoglobin changes. • The oxyhemoglobin and flow transients correlate with ischemic brain injury. • The results motivate future clinical research on transcranial detection of SDs. Spreading depolarizations (SD) refer to the near-complete depolarization of neurons that is associated with brain injuries such as ischemic stroke. The present gold standard for SD monitoring in humans is invasive electrocorticography (ECoG). A promising non-invasive alternative to ECoG is diffuse optical monitoring of SD-related flow and hemoglobin transients. To investigate the clinical utility of flow and hemoglobin transients, we analyzed their association with infarction in rat focal brain ischemia. Optical images of flow, oxy-hemoglobin, and deoxy-hemoglobin were continuously acquired with Laser Speckle and Optical Intrinsic Signal imaging for 2 h after photochemically induced distal middle cerebral artery occlusion in Sprague-Dawley rats (n = 10). Imaging was performed through a 6 × 6 mm window centered 3 mm posterior and 4 mm lateral to Bregma. Rats were sacrificed after 24 h, and the brain slices were stained for assessment of infarction. We mapped the infarcted area onto the imaging data and used nine circular regions of interest (ROI) to distinguish infarcted from non-infarcted tissue. Transients propagating through each ROI were characterized with six parameters (negative, positive, and total amplitude; negative and positive slope; duration). Transients were also classified into three morphology types (positive monophasic, biphasic, negative monophasic). Flow transient morphology, positive amplitude, positive slope, and total amplitude were all strongly associated with infarction (p < 0.001). Associations with infarction were also observed for oxy-hemoglobin morphology, oxy-hemoglobin positive amplitude and slope, and deoxy-hemoglobin positive slope and duration (all p < 0.01). These results suggest that flow and hemoglobin transients accompanying SD have value for detecting infarction. [ABSTRACT FROM AUTHOR]

Functional near-infrared spectroscopy (fNIRS) signals are used to measure relative changes in oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) concentrations. Brain response studies constitute multilevel or nested datasets formed by different parts of the brain of individuals and multidimensional datasets. The changes in brain activities under specific stimuli are investigated with the help of statistical analysis. However, these studies ignore the dependence structure between the repeated measures of the same subject, which may cause inaccurate or incomplete findings. In this study, we adopt an advanced statistical method into HbO data controlling for variability within repeated measures of each subject while testing and measuring the degrees of the statistical significance between-subject factors and explanatory variables. The changes in HbO are investigated through a linear mixed model, taking experimental and demographic variables into account with open access neuroscience data. The channels nested within subjects are considered random to capture the differences among individuals. Our findings reveal that n-back conditions and mean response times of the subjects have statistically significant associations with mean HbO. • Significant contribution made by fNIRS optodes nested within subjects to the model. • The mean response time is significant for the changes in mean HbO concentration. • The mean HbO concentration differs among 2- and 3-back conditions. [ABSTRACT FROM AUTHOR]

Risk of sudden death in multiple system atrophy (MSA) is greatest during sleep with unknown mechanisms. We compared nocturnal pulse event frequency in 46 MSA patients and age‐/sex‐matched controls undergoing overnight pulse oximetry. Nocturnal oxyhemoglobin desaturation indices and pulse event indices (PEIs) were recorded, and relationships between pulse oximetry variables and survival were analyzed. MSA patients had lower PEI (3.1 ± 5.3 vs. 12.8 ± 10.8, p < 0.001) despite greater hypoxic burden and similar frequency of respiratory events. Nocturnal pulse events were not associated with severity of daytime autonomic failure. Two MSA patients had suspected sudden death, both with severely reduced PEI. MSA patients have fewer nocturnal pulse events compared with controls, despite similar respiratory event frequency, suggesting abnormal cardiac responses to sleep‐disordered breathing. Whether this contributes to sudden death in MSA requires further study. ANN NEUROL 2023;93:205–212 [ABSTRACT FROM AUTHOR]

Hemoglobin (Hb) possesses good properties of cooperative system and it normally executes oxygen and other essential items via erythrocytes in the body. The chemical action of Hb is to combine with oxygen (O2) in the lungs to form oxyhemoglobin (HbO2). Binding of oxygen with a hemoglobin is one of the important cooperative mechanism and is an emerging mathematical research area with wide range of applications in biomedical engineering and medical physiology. To this end, a mathematical model is proposed to study the fractional saturation of oxygen in hemoglobin to understand the binding effect and its stability at various stages. The mathematical formulation is based on the system of ordinary differential equations together with rate equations under different association and dissociation rate constants. The five states of the cooperative systems Hb, HbO2, Hb(O2)2, Hb(O2)3 and Hb(O2)4 are modelled and the Hill’s function has been used to approximate the binding effect and saturation of ligand (O2) with respect to various rate constants. Also, the Adair equation has been employed to interpret the saturation concentrations of oxygen in hemoglobin. [ABSTRACT FROM AUTHOR]

BACKGROUND: Hypoxia influences standing balance and vestibular function. OBJECTIVE: The purpose here was to investigate the effect of hypoxia on the vestibular control of balance. METHODS: Twenty participants (10 males; 10 females) were tested over two days (normobaric hypoxia and normoxia). Participants stood on a force plate (head rotated leftward) and experienced random, continuous electrical vestibular stimulation (EVS) during trials of eyes open (EO) and closed (EC) at baseline (BL), after 5 (H1), 30 (H2) and 55-min (H3) of hypoxia, and 10-min into normoxic recovery (NR). Vestibular-evoked balance responses were quantified using cumulant density, coherence, and gain functions between EVS and anteroposterior forces. RESULTS: Oxyhemoglobin saturation, end-tidal oxygen and carbon dioxide decreased for H1-3 compared to BL; however, end-tidal carbon dioxide remained reduced at NR with EC (p≤0.003). EVS-AP force peak-to-peak amplitude was lower at H3 and NR than at BL (p≤0.01). At multiple frequencies, EVS-AP force coherence and gain estimates were lower at H3 and NR than BL for females; however, this was only observed for coherence for males. CONCLUSIONS: Overall, vestibular-evoked balance responses are blunted following normobaric hypoxia >30 min, which persists into NR and may contribute to the reported increases in postural sway. [ABSTRACT FROM AUTHOR]

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